Hi,
On 2022-11-28 10:50:13 -0800, Andres Freund wrote:
> On 2022-11-28 13:37:16 -0500, Tom Lane wrote:
> > Uh-huh. I've not bothered to trace this in detail, but presumably
> > what is happening is that the first CREATE RULE converts the table
> > to a view, and then the ROLLBACK undoes that so far as the catalogs
> > are concerned, but probably doesn't undo related pg_stats state
> > changes fully. Then we're in a bad state that will cause problems.
> > (It still crashes if you replace the second CREATE RULE with
> > "select * from t".)
>
> Yea. I haven't yet fully traced through this, but presumably relcache inval
> doesn't fix this because we don't want to loose pending stats after DDL.
>
> Perhaps we need to add a rule about not swapping pgstat* in
> RelationClearRelation() when relkind changes?
Something like the attached. Still needs a bit of polish, e.g. adding the test
case from above.
I'm a bit uncomfortable adding a function call below
* Perform swapping of the relcache entry contents. Within this
* process the old entry is momentarily invalid, so there
*must* be no
* possibility of CHECK_FOR_INTERRUPTS within this sequence. Do
it in
* all-in-line code for safety.
but it's not the first, see MemoryContextSetParent().
Greetings,
Andres Freund
diff --git i/src/backend/utils/activity/pgstat_relation.c w/src/backend/utils/activity/pgstat_relation.c
index f92e16e7af8..1158e09c24f 100644
--- i/src/backend/utils/activity/pgstat_relation.c
+++ w/src/backend/utils/activity/pgstat_relation.c
@@ -158,7 +158,7 @@ pgstat_unlink_relation(Relation rel)
return;
/* link sanity check */
- Assert(rel->pgstat_info->relation == rel);
+ Assert(rel->pgstat_info->relation->rd_rel->oid == rel->rd_rel->oid);
rel->pgstat_info->relation = NULL;
rel->pgstat_info = NULL;
}
diff --git i/src/backend/utils/cache/relcache.c w/src/backend/utils/cache/relcache.c
index bd6cd4e47b5..69237025c20 100644
--- i/src/backend/utils/cache/relcache.c
+++ w/src/backend/utils/cache/relcache.c
@@ -2626,6 +2626,7 @@ RelationClearRelation(Relation relation, bool rebuild)
bool keep_rules;
bool keep_policies;
bool keep_partkey;
+ bool keep_pgstats;
/* Build temporary entry, but don't link it into hashtable */
newrel = RelationBuildDesc(save_relid, false);
@@ -2666,6 +2667,8 @@ RelationClearRelation(Relation relation, bool rebuild)
keep_policies = equalRSDesc(relation->rd_rsdesc, newrel->rd_rsdesc);
/* partkey is immutable once set up, so we can always keep it */
keep_partkey = (relation->rd_partkey != NULL);
+ /* keep stats, except when converting tables into views etc */
+ keep_pgstats = relation->rd_rel->relkind == newrel->rd_rel->relkind;
/*
* Perform swapping of the relcache entry contents. Within this
@@ -2720,9 +2723,16 @@ RelationClearRelation(Relation relation, bool rebuild)
SWAPFIELD(RowSecurityDesc *, rd_rsdesc);
/* toast OID override must be preserved */
SWAPFIELD(Oid, rd_toastoid);
+
/* pgstat_info / enabled must be preserved */
- SWAPFIELD(struct PgStat_TableStatus *, pgstat_info);
- SWAPFIELD(bool, pgstat_enabled);
+ if (keep_pgstats)
+ {
+ SWAPFIELD(struct PgStat_TableStatus *, pgstat_info);
+ SWAPFIELD(bool, pgstat_enabled);
+ }
+ else
+ pgstat_unlink_relation(relation);
+
/* preserve old partition key if we have one */
if (keep_partkey)
{
